The present invention relates generally to sealing rings for sealing machinery lines together. More particularly, the present invention relates to an improved “U-shaped” composite elastomeric seal for sealing together fluid line members such as fuel injection lines and fuel ports.
The industry uses sealing rings and gaskets in various applications for sealing fluid lines such as gas lines, chemical lines, hydraulic cylinders, and the like. For example, “O-rings” are commonly used in fluid sealing systems. Particularly, conventional sealing systems can comprise three components: a) an O-ring made from a fluorocarbon material; b) a metal spacer; and c) an O-ring made from a fluorosilicone material.
A conventional three-part sealing system using O-rings and a metal spacer is shown in FIG. 1 herein. In FIG. 1, the pressurized fluid is shown as flowing from the left side of the sealing system as indicated by the direction of the arrow. The fluorocarbon O-ring is located on the fluid-facing side of the sealing assembly, i.e., on the side where the fluid approaches the assembly. The fluorocarbon O-ring provides good chemical and fluid resistance. The fluorosilicone O-ring is located on the opposite side of the sealing assembly and provides good temperature resistance. The secondary, fluorosilicone O-ring acts as a secondary seal in the event that the primary, fluorocarbon O-ring seal should malfunction. In this manner, the sealing system provides a double-sealing effect. In general, conventional three-part sealing assemblies provide an effective seal; however, there are several disadvantages associated with such systems. For example, the costs of such assemblies are relatively high, since three separate and distinct components must be installed in a specific configuration. In addition, these systems are typically assembled by force-fitting the components together. The industry would prefer a sealing system that does not require such high insertion forces. Further, O-rings are prone to rolling during installation of the rings. Rolling of the O-rings can cause spiral failures during operation of the seal.
In addition, the industry employs U-shaped and other configured seals for sealing machinery lines. For example, Scott, U.S. Pat. No. 4,013,299 discloses an annular sealing ring comprising a U-cup having a pair of lips for forming a cavity therebetween and an elastomeric expander ring mounted within the cavity. The sealing edges are positioned on the outside of the lips at a vertical location at or below the horizontal center line of the expander ring. No compression forces are applied to the sealing edges above the horizontal centerline of the expander ring.
Wu, U.S. Pat. No. 4,141,563 discloses a lip-type shaft seal for rotary or reciprocating shafts. The patent describes the seal element as being made of an elastomer and having a C-shape cross-section. The toroidal cavity of the seal element is filled with a ring of an elastomeric material, such as silicone rubber adhesive sealant, which prevents collapse of the seal under high internal pressure. The inside of the C-shaped seal also includes a garter spring which provides a constricting force.
Timpson, Jr. et al., U.S. Pat. No. 4,687,212 discloses an annular sealing ring with a generally Y-shaped cross-section for sealing between a piston and the curved wall of a cylinder. The sealing ring includes a base with one or more horizontal ribs extending outwardly from each side thereof an pair of lips with sealing edges. The lips are spaced apart to form a cavity therebetween. An elastic, expander ring is sealed in a portion of the cavity so that a void is created in the cavity below the expander ring.
Muller, U.S. Pat. No. 4,723,782 discloses a sealing structure comprising a sealing ring having a groove. A rubber-elastic stressing O-ring is fitted in the groove at a certain initial tension. The elastic stressing ring urges one area of the sealing ring against a face of the groove in a sealing relationship while simultaneously pressing the sealing edges of the sealing ring, arranged axially one behind the other, against the shaft to be sealed off.
Kiesel, U.S. Pat. No. 5,269,537 discloses a composite radial seal for sealing the rod end of a hydraulic cylinder or suspension strut. The seal includes a high abrasion-resistant elastomeric seal ring having a U-cup configuration with an elongated body. The body has a pressure end and non-pressure end. The seal further includes a highly resilient energizer ring which is filled and sealed within the cavity of the U-cup seal ring, and an integral anti-extrusion ring which is carried on the non-pressure end of the U-cup seal ring.
In view of the foregoing problems with conventional sealing systems, it would be desirable to have an improved composite elastomeric seal. The composite seal should be an integrated structure comprising an elastomeric portion and a harder, more chemically resistant portion. Such a composite seal could be used to replace conventional three-part sealing systems as described above. Further, the composite seal should have a shaped contour so that it can provide a tighter seal at the interface where the line members are coupled together. The present invention provides such a composite elastomeric seal. The present invention further provides a sealing assembly comprising two fluid line members coupled and sealed together using the composite elastomeric seal of this invention.